The invention relates to devices used to perform diagnostics in communication networks equipped with a bus comprising at least one electric wire on which a voltage can be measured in a non-intrusive manner.
The buses of certain communication networks of the aforementioned type comprise a limited number of wires (at least one) to which communication equipment can be connected in parallel in order to exchange data between them by means of multiplexed frames. This is for instance in the case of networks such as CAN LS (“Controller Area Network Low Speed”), CAN HS (“Controller Area Network High Speed”), VAN (“Vehicle Area Network”), LIN (“Local Interconnect Network”), ARINC (“Aeronautical Radio Inc.”) or I2C (or IIC “Inter-Integrated Circuit”) which are used in areas such as vehicles (including automotive type vehicles), industrial installations, in aeronautics, consumer electronics and in the railroad domain.
Because of the high number of connections involved in such networks, they can be the object of numerous and difficult to detect operating faults (or breakdowns). For instance, they can be the object of a short-circuit between a data transmitting electric wire and a ground, a short-circuit between a data transmitting electric wire and the voltage of a power network (for instance of a vehicle), a short-circuit between two data transmitting electric wires, or the outage of one data transmitting electric wire.
The larger a network the more difficult it becomes to diagnose the origin of an operating fault (or breakdown) occurring within the network. Certain devices (or tools) such as those described in, for instance, U.S. Pat. No. 5,491,418, U.S. Pat. No. 4,957,847, U.S. Pat. No. 4,796,206, FR 266641 8 and EP 0231 607 are available for diagnosing breakdowns. But they all have at least one disadvantage, such as for instance the need for establishing, with the network, a bidirectional communication according to a predefined, and therefore intrusive, protocol, and/or the need for using relatively powerful processors, and/or the need for complex programming, and/or large overall dimensions, and/or the need for being operated by previously trained technicians.